In recent years, along with the rapid growth of needs for high frequency transmission of space technology products, national defense technology products, and mobile communication products, circuit substrates having low dielectric constants and low dielectric dissipation factors have become one of the focuses of further technology developments, in order to comply with the needs for high frequency transmission. Liquid crystal polymers (LCP) have electrical properties that high frequency transmission requires, such as low moisture absorption, low dielectric constants, low dielectric dissipation factors, and etc., and characteristics of high heat resistance, high size stability, heat conduction, chemical resistance, flame retardant, thermal plasticity, recoverability, and etc., and thus have become the main stream of high frequency flexible substrates.
However, due to the high difficulty of current film-forming technology of liquid crystal polymers, the liquid crystal polymer films have severely insufficient mechanical properties along the transverse direction (TD), which become the main restriction of treatments and applications of flexible substrates. Therefore, it has become the key to the current progress of high frequency flexible substrate products to develop liquid crystal polymer films having excellent mechanical properties as well as high flexibility.